SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd53e146e9eda85555fa2d4fc64549bef71f2d6f05c2209b5f03c424ea3d62ac4' 
  AND token = 'eRoM0nJAWhB0TvJamqD3w3ygQJBOvoTTfuRIjKDkLT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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