SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5a812b0571593ffe668f31ba9ed1b6c85e0ba5fa7ec7f62cb3f095d2e00344b' 
  AND token = 'BP+LzIpH/axpGk/RsjK6fURmWf/fgYBZoE/hMBhzEmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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