SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d5af15bfd3c2706faa15cdf9255542aa4e330b582cde5898c970d573c0fd755' 
  AND token = 'jCjCpg/MToDE4weINI1JVXffvmpfY0iQiGaSdoWTIes=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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