SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5388465ef400765960642a2fbe250b869f0af9645d7bf8ec58556afcd028040e' 
  AND token = 'YzD7CdQoeGxkGP0/vp9IaS3zIb1mQBUC6cA0u0/rELM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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