SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2cac0a0adf15ff0bca3cce7f50e1b3266057db543c39d52c1bcbc228fde1837' 
  AND token = 'jMaFZJcDwy55b+nVySsQdlaFMbkWtqF7HCbhJpSMXUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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