SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6afb1b0795276be0062c9100c652c66664108dd9a7ab659d86ac01db7db0af55' 
  AND token = 'ylwoVFpOZKt4lp+5Ish8ZYNbX2tw7Rx7GGNxkAI35G8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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