SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7430fb1afdff6e8bb62b1848ab2e038a9bd907bc7105511d24bcfa89f319906' 
  AND token = 'LKa/pSCwRVJOeSWtmRfnw+jFJiUuqsm2uTac2n0sk2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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