SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '008ceff75816429d9880096585832d434cf30d26f56e9b7af7a903da2b38fd82' 
  AND token = '3/uxw00Mvu7SSPOAaQ1cB4FiDeFjjtD+FFHWKwx7eI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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