SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83a81494caf2f3968728c9c436c09dc1dabdfad7451b1777f0af3df4627955ec' 
  AND token = 'J4TP2yjb8z7Oj5kmuRq4nxS8vDcSKlqg8prf3JFCQZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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