SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21083cab693026fa1b3fce13c40ed80dc8c75c9b46f9720bbe645e80648036a9' 
  AND token = '1+9O7clpdVfw17hB2XZJbNO7rf1ReT1ozmPtiqvLTQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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