SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8398b3ef3cece3b10b011064d16957adcb394fa9f38f3aef65cc28d95138aed1' 
  AND token = 'SsLsNQBzHPTsLLPfzstC96MzYd8yz/vCxfpy94bqeLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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