SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d4ed32cb56487621a0cb3dde26548213ccee3d8dc522328dfae728f7e356a5e' 
  AND token = '6jFNaLkZeV0asJvBQkCJuLPtBqTBZIRxIh1/jgf0dMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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