SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6aa615a4aa8f9dac272a0accd3addd62cc474648fd0ba54d4c12c47d2f09ca3' 
  AND token = 'iiD9MO6ywNeyoYaYbhZJJIdk4SZVglPjRwFoY2D/mIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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