SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e89240b01dd3021cb99235e0eeba0420667ab58b261ced8778ee3fd6c2c32b9' 
  AND token = 'ciDn+Ct9b1jMmZ9TpUCqL3UQOGNmSpFemRW67yOlb2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}