SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '814791bbad8028c010fd4a1384955e3d51753e467900af31097a0386f99e44ac' 
  AND token = 'FGtcXPTgQ01nO2TzLz3UzzdMw5HFofTRY3YuaXET+2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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