SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b7444561e36d21800795984ed8bb523f587e575d345a4f86dcaaa9da5f88092' 
  AND token = '2SBbjZnqAiZXYzMlkqjH/UQmzhHmtXWwp18tuis9xp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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