SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23b61ccbadc5988e6e396f59854f6813f5d7a5ffcae84fb4519322f6861de7ce' 
  AND token = '5aV2agQNh/zi0ZgVR8znXMGq3bzUlzbpXtf+YpjmAdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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