SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f956ec417ad38a67ad2fb8862a7e61f8ca452183257a01017132acebf0c1d33c' 
  AND token = 'b/90HHaWZRFHtrxA7CnOC+mxPHx9w0tRQCufKK9g5wA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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