SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac0998d5066dca6ceadf3cb091c13a38750bbcdd7527c01ccb20a7d91665a0f4' 
  AND token = 'NzDmjoVSL2A45NnUGnnrjfAA4mJoY+7VZSUKkc8FEFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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