SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '624fb20e2f6bd526368df01d021a6dcb515f15b420ae67f380531986778215cf' 
  AND token = '5LD1AKXUCQWXmqJwOnEFUsKVv+5ZHjLxXUvi2P3ukyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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