SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71c7bc08b98462788af04c23585e0934206dba4ab68ba05433a60c27bcc8179c' 
  AND token = '/47p7670rGXvB4uCa854ckL1iI3ikkBvcqZ/wqVCRWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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