SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc74f2a8dd8e4329f4deffa9d7a3d361d0a8a7b57e7486f0b92c737a991e8c1a' 
  AND token = 'vqt4uRXiqV/hNj5YaSZDXCDJkF3GAS60+6Z/S9WJ0W4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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