SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b877c991888727161042d3e6360a90fd9c800386959a445ae41c4064163491a' 
  AND token = 'Zq++l5bnarUiCBzHo3qDpDNfHhGtYotdtOPRxJXFujY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00068

JSON explain

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