SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50f493f3fd918e59a6350bd42bc74a57570e4085288d63c6065ec94addb4ad82' 
  AND token = 'Xv03zOaxGRafUO8SVVc91zgztm6Y/wKHOGJzfyYUivs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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