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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c4323203267eafa13cd532e1a120d0c7be4a5f7c0467be33491977d8af9b03' 
  AND token = 'EXgdhXNPf1KVJVY7Cad7fLoFx1fmoB9UY1NmaBrVE4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00093

JSON explain

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