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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e53cf0a220ce314fec8c0b61bfa0e8e6e19039c4282c1ad6c3023fe18cdcc88c' 
  AND token = 'mF+6FGsqNt5kvr9NtwpgBtfe3msYGC79P0VKk0Y+ews=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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