SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c3f536a6a71eaecd5b6f0ed59bddad0d8a721f05c1818561953824b7317bcab' 
  AND token = 'eWSyG4uwEB4j//lK4QnqItmjOwL5YW1w2kyY8RIK7eI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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