SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b55a53291964e34f5a63aa21f7ce27cf3566da5c2a9ef0f8e436ed6461fc90d5' 
  AND token = 'hH1UZngfGKdwjmulbkLBhAo0rjjNyX7/yUnZ7vTpflc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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