SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fce495eb5e1c68df2ff30bd390dd96d9dde027e4255f48233399d6e0cd44e2c2' 
  AND token = 'KgQljWfXGhhVlrlvI6z1VhgF99Sui1pb2j5BpY1i6fo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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