SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd86ed6b162e50ffe993f3721653d975d5759b4e91f077f981cd08839c4eef120' 
  AND token = 'llapKl1lNdAK21dsrFz59Upi0iSfwpToteiTLWbBMYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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