SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dce5bf154b8e3a2656c4e080be9fbff56c1228464649bcf5868e23f260db99d3' 
  AND token = 'sdvUVhwFR877wpEcKzq3lvV5O867JXa+IEVBJnxS/+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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