SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c47136eb7bfd25729ad1958b1b90f3d538613c9309e1e80b41dfa10b2ca517f' 
  AND token = 'CTksu6hhYKgf0qinlYVm3HeA6wsFo6SxWhzo4YU4Bn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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