SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '74b321c1f8fdbafd6d211acaaab315d4afc4352f6726a4de4e12f37f5c2fee55' 
  AND token = '7k58nasUUviSds+zISPeRIadKOt7rbt8GaYIDorrCpE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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