SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '56b3a347a7b182b6887a03594b30755f81ac32813bee78d70b8b35aec0d4f83c' 
  AND token = 'by+PZ0A5sz/3AUxlUU+JpEoIolXcjITGHLbI+rBDPNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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