SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86c4e7d54720f93958550e9d849e4e1b2b0faa6594437d22b8ff7d3f7251248d' 
  AND token = 'AZ7CnzUG8Xs1r8MjPnajgtx2yKuzBmHZS90/Nh07lGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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