SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab50600c241d20d76e56d84d5f208eec2acefb74a051942c7bcd63ffdf473a5a' 
  AND token = 'fs9jSs59FJFvzHCOfLIxODWpLfG5+PGbtDCDeB9Lgx8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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