SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a0c6b762a1508a2c632eece5411e58d95738fa5c43c49cdb747b4f9df76e88c' 
  AND token = '8qaxJ7WDZxVwcjQp2J/bmC9DELKGItBslJOi4xCp0+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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