SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68797f56b2311e24606e2abe05a7fba607fb1f5c849418c101448473d0915f56' 
  AND token = 'bd5FmAHsQzCQoSvQQU3b6yMXIqXi862CxidhBBFJ9kc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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