SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21b7c9a4d883592620eefaba3e8d0579465fdb34d11c47e1afeb8c90f74f6672' 
  AND token = 'vCCDB0epylPYuPsq8tSvuCzw+K5B6WNSP9FInmoxXWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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