SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30737a3f9a1d714b966072f91db9b7787a29989c3c30ddc1286209cbd6e2f5fd' 
  AND token = 'NwmUKnbGUkk3bTTzk2fXxQSMY1msqvt1dtVGbzJeYUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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