SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a647dadc8e9466cdebb3ec6137d7435cbe6bdd30c62d37b54de4d795c2388574' 
  AND token = 'FgcfpWeEV04+qlDj8h2r9Ees+ccrpzNvdu0vIYXDmDc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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