SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81ea0b8bcd3a2883c710a2877eb15ddfb41817719c9e7e631ad48e0def1c6cdd' 
  AND token = 'nsrIhtJaV9AaKdhYsxdfhgYMLMr3Lj7zjbLs5VXz1Sg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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