SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a4d0fbb78d6eebdf5e9a23e800e0025f18936a8a7d20304d0550986009eb419' 
  AND token = 'qmpMBcVNZRv85U1gcXsI+nHFrXyEtFsODxtIidhLbJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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