SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a03a386075d061b69aad4ede40d324a202357468afa8871ca32332d3c1dda9ec' 
  AND token = '67XpQLg54n8pXHTjkgTRmcsE7S+7Q6u0cbiUJ/DF37Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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