SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0d2128091116b52f6835e6c353f751d24987b12187738e46720451384217cb3a' 
  AND token = 'ukTX6uLvROnzcIblUFdAgtgWgvzUcVfpTDh8XPGcy9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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