SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c37a9ccaf17f2bff33efed92583810700aa0c497a11280d49e9aa9acfc64e0' 
  AND token = 'bW68C79D9xt+AL2eeONHFpU0Qgfa0AwX5RXQ+uBehn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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