SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '200b396efc82229d82e8afef59279ec84694cca40498fcde04b4fb55e9c97e75' 
  AND token = 'XPmqkd5YYVKUIKYMUBeslaEmBDSW+cxov/mILZ0xXNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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