SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4792bb27be565dace4dbb7f88751e255977a40666646340c473dd122cebad344' 
  AND token = 'ym4GiBLxUlaQpQcyTsvkPuSYsrbQz2d7b7bppwznNAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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