SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '248dad8fa3cdba9d2cd6e7950245740a8acec8278593403953d25ca2c404962a' 
  AND token = '5xpXvXyItkU1wegTbJbdqdP+dQ6/GYkkPnojxMcFlOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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