SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9c873490a4571947e1e38889ac6193d02a1053c468697ac12c462771b45f473' 
  AND token = 'C4huERG2xhOF/mS8PJRSvQ/5GVXsKIIq9HIP8TQDHBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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