SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3dc9cfde3ebbfe81498bb98c0d3adfd8332759543da5427ec4cf68c7ac350fc' 
  AND token = '8SoJtuUwYmAj2jrMI4KWMSbb0vCraVWCWqzP5o0OQWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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