SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'e28da1555b7cf10021666977ab3f709fc124f481864359cde87686e95a4bcec8' 
  AND token = '7pvwygAfsWERPgPZft3+6RZEHueu2AxhZzVghNWB2Zs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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