SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c90c723b2ec5c8241ba6feaa185036da6ddce665c5d75e08d9e871265244e181' 
  AND token = 'seh+MfBncZyKbGC6lpCxAqXLWsj0pNHIwprfLLrJ0RI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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