SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87b9cd75dea5b8474e20465fd57bf8bee57913c0bf6ed3d73135f3a903eb98dd' 
  AND token = '/A6amoSKEp8QOYvPJjARGGbJW2UBQLxUAhT5oqAG7Zk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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