SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fc3941cad093a995e32db0a6b1eb0ff85d5b3a6fad4059e3ca8d7867cfe6595' 
  AND token = 'c1tznelW8pQEhNwwYEktyVqzv/lohn6IMNhw5hedAc8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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