SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c8dfe047fa6811b06615bc86a0b37e1b5fafe72273361fddb2c6988139779cf' 
  AND token = 'ULg8vU3wYhBKdgjHnM8GX0kje3oNF6+LFWM18hMESPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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