SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d23851220b5dea191f9e1ad142e06856f52340a48715bc9e7c57aab743e6c17' 
  AND token = 'NknGjfugj4DkOE+FSJzg19f4M6RXhJCiHuFZBEhLooo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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