SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc249d43fb7825a05a84dd96e20ce1155c9e34755cc082ea9a8e58d07a878348' 
  AND token = 'ViQdfHInU9DP5Ty4nGaputROgkZll39eCp1JwLMjlFI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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