SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28e852b530da87bff83f696220e1e1c59b1da620fa885bba837c8a1d30fa0a94' 
  AND token = '7USlQJPAoNErZRaFTbNAupACCsfhxXss/paIVmOHUzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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