SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e4218954368d6124f2cdc1148903483ac0f8a35f12b5a57b2c0f777fffdd279' 
  AND token = 'oQoMgUTF7zG5sPOp6ToWZJ5udjgl4KOCg3WFsXt2Y1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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