SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70798cee990c91f2d8d015817716cf4324bca4bfba5fe09b6b3ddaa0bf805941' 
  AND token = '3CJsZFNrFsOKlS8upfZG0lbDzZjZMJ9uIjyWHpn1SCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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