SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6cda8bba48bc16edaef24489071bffc141824700af9800b113f2122f5d5b99d' 
  AND token = '57/G+wRJzQ30kIhKHpz4yCG5xKvUAXXjdeLACkYXlSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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