SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77273389769ba01116d4007b34f8d720d019c71a12d45c41a89122b2887856f1' 
  AND token = 'c1urMFzO4oa/tS8gzmm37ZZR4YzTLCLLBrR5VVlBIvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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