SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a5b893cbb7f9e57ddc02f0292db17ae72c01bfede4cbafcb45b65f2e92aa225' 
  AND token = 'b696F6wun0VwgC49kNzy55nYS4uwPs7A6gtSbykXT2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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