SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bcb5653442749d6cf253a66727564eee9ecb146600c135028bde254ef421c24' 
  AND token = 'xWbe5uc1UY3xglHP7ZXmgtWC55S0MD2XIBGH1lKAojI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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