SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f6cfdd83e403edce326ed51b5b2862b45f83ffb5e0b92600450c944d5ada3e17' 
  AND token = 'I96FWJCrB+AleGrtc41T8w1AazlPJw3gspIOqBORz/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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