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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5651dcd2c5eda1fcc46fcd20090fc90a4f6db567c6bd7e213a12f87ae4cb8f7' 
  AND token = 'NN4xtyX8I67WAwumqZH9PVuecjYS0ZlFFY+lTPiPFEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}