SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cdd31cefe931201bc4a12538b0a0ae82f08941cd029be64557b26e4b5cd0d78' 
  AND token = 'jOVqLkucD8/ZQW2stOKR8YtUpHJoXWNtmI1RCKSQNsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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