SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e52330101216781aee874c8c7fdc88761579aeeeae99dfdeb5f429e3e7a1d08' 
  AND token = 'mDJvGC/h7YFTMGJt5uoB32uZWt9bfpF7pBVfaLEMclo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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