SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21079cacc209659f38eece4bcecab0ce775cc8fab7561bf2995b175227d22f4b' 
  AND token = 'i3SWo40VdXav1UgTVkgHpYTWN0tJNKG/osbD5vLtOoE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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