SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55f109129c30c761d37d67361c06f0d78be0c44b500577a53e8c59ced76f4cbd' 
  AND token = 'G/tSnFUBXhnElFNBbFdX0IPKMvjxVHlA/lIxWYtCrlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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