SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '461aaf2a81570c4a5a1f62b28f21d9a793045e68619c669a66400e17da6fad9c' 
  AND token = 'JpHxc0HTBw5eoYGaqthhjb3JiSUWewlmjojwyrVXXeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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