SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9905aea6c21bc61d70f0b5d5e0848fddfe84f0b7f90597909baf4072d546343d' 
  AND token = 'yBxJvr9GiFVjf2GC8p/TUpuGlvK4YB/DpNCnM9VT8o4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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