SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb9a973189ceba049a563fbf31f3d36bead78e5b7e080a8d21221d9176e93f89' 
  AND token = 'USTCLbXyZDnF+Pf2j5RfZHjT3oijBdGMRxwCr7vhw/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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