SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '746355c5dbdef1eb6a82e90ccf684235974dc6ac411f8778d483e8a1709ca536' 
  AND token = 'X/xM3b1v1KqhlDCOZxhpaVFZ/oA01JjxhUjLoRbbz5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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