SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f39190bbef382e4ea86fd621daad07abcc7997246efe618f145257c62d8d8ffb' 
  AND token = 'Ggi3v3nsNr/rfr4GKQnrO87AKkEN9NzW9Z2YbUMvhI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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