SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd687072de1164e30ccc1b470cb64ea20f48dc279b31e04381c6b8774e695a57' 
  AND token = 'P18kfAfUcKjKgtclULY2osG+fzxgj7E434asywDZ3vM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}