SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45a9e06c457186b3587a3a7991b315b268e8d1be38cc4939a36339516a68a378' 
  AND token = 'efSykichOEgIcNqwOygx7yNmXU14sEPjW96vR1nzFeY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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