SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a9239bcbc283c446790331394810c71bb83b92cc15bdb4d481c9f22a1535125' 
  AND token = 'KmIotbLqMHgjAUyzHhsQ9YFgKFpiMCu5YZjU+dy/uZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}