SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b091fb2d9c7dbbd0399700c82b9a29d3daa16b511d87a992547fa50a16302970' 
  AND token = 'rYI620s6AVkhtn2vg9iEio7C8ca2hRbH9zKrnBUijug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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