SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dfc5cd4d3b75c7d10fc8a961b52db94d517dea2482caebb813098d7ea4ca4d6' 
  AND token = 'xSWKkIKCdsfknnijIxduGHiuzrhW3cThlTjf/dePR9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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