SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9e87ca474efa16580d1896d156739ca6e7660c9a2cc41f58dad38b23adc69fd' 
  AND token = 'U8lJULOeaTZBJcwMe5jtcS2dM+M83KGWapsHOUchnPE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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