SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a39f1cfb40ebd11e2aba42726cb323979d139280a1ec1c9dedc4b81b5e918045' 
  AND token = 'eu66V+1kjC8s69OjeqK3mKfcxmwIKzTmUEUFCYfohUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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