SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d6dc670e26f80dc2f82ccd070249280477ebe7926543c19d7f20427e07cea11' 
  AND token = 'b71YvzVJhkoX7zonf5/7WiE+ULDVMbljmptNXbZmX1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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