SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50139b3440592fb8c792fa73809af58919832de9739f6000a4c7525d2ed0345a' 
  AND token = 'UxUuu57WfqPsEzQ9xti3Mxl9bWB4H7aPH/RI79EYO4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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