SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76b6925612913f8c136e72c8c256841281d658c8c5a2d55bf020373d5568f148' 
  AND token = 'OSYVNTIwbmlSz//ep5WScubnURQFxh4AGQaPvvB1kK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}