SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af58691e076684dd6fc0c1dfc399a470671a245c4c3313967e13037b9da8ec95' 
  AND token = 'DhciYzmGkKjqUWlQa+57dbexEDTsdRIHQlBs4LU2lPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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