SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'ccf8559453728886bab83c89c1e667254174430b4d0f4ba92ea9eb7b12a18204' 
  AND token = 'nFy0/66HaU2EQeqjVQO7HbUx+JxPgVpVzdyjthFOGos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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