SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a046bb60ca91b47019df52cf15e498088542ead02a3191f070b1e40cf3ead411' 
  AND token = 'seZC8mivId08SiBFsx+ltx25dS0Btdtw3Ugexlnhm5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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