SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c76934948f2b036e29bc625b6bdd778c96b7b5802f52c45747049651c152f5e' 
  AND token = '4KtuD/OaDSk9gBY3MmOhYxkOOEWBiZY1UYWJk1O84NA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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