SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c312e1a589c586eb6879837359fdd137c87e8618315f14209c5453087dd950a2' 
  AND token = 'vxJzquhu3p1TzV65Xlbk0WABdqyADMnq7Ofs7g6ybLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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