SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '193f045c3046cec4c6f107648b87e23af19cac1be686151cd20a636c1bb00fb9' 
  AND token = 'bRU5S47wjvh43CYjXjmYGNoUldJH6Aimlu+y3527BS4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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