SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec3b6afd83c01563714c99eb2501c95e53388a9f8f6f7ec982abc2a794fe8ddf' 
  AND token = '38+1qzYjYYgZ4pN4L7RJJFpYnBzHXrNFzhg6HYUF9lE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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