SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf53d80da37aa12dc03381d83adc1b714d416956279b796b984051b95c74e0e3' 
  AND token = 'dszn9sBY+GNQqRTDGxLMrQGEaDmG1kWIzevX/4elWRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}