SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0bcfdc05ccb68cc379fefb9adec94dab0b8d5a91e36602f92395858926d3826' 
  AND token = 'kMNEJ4hGE8xErP/EBmuoUfjAiaxUHd7rHqYsTvUGZAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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