SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '669174e9cc44b1381126806ecaced2724cbeaa60bab69826270e747f89db208e' 
  AND token = 'oR81uzuqeLemvboyINgiXjoeT8mqA1tgVc24Z7Cifbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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