SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39b0975d6a28b476fdfd2b104a89d05c7a23ba267936a1443ff2772e38a95dbe' 
  AND token = 't2AG7ztXOaH6Hvc2BBXgjcSlaBT65VwwYkrGq3PJxro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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