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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b40935fcebb304d290400cbde14e225b611113a5dff99a8d392229d1d28c91bf' 
  AND token = '5uZFZSUiJMmKSY2ncpqrItT0+FHjpyzCW2rGj85WMOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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