SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b91f321afd7b461bb3781e5085d3dab3e4d778a3e113d075f5e037a3f7f437a4' 
  AND token = 'HQ3/ksLNIwY1oBiLTzzdLuCO7FeJ5i8HAdcrwTCZkOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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